How to fix Error: Error in function call - Call to function map failed in Terraform

Search your Terraform configuration files for calls to the map() function:

grep -r "map(" *.tf

Note the locations where map() appears. This might be in your main configuration or in imported modules.

Convert all map() calls to use native map syntax with curly braces. The map() function was used to create maps from key-value pairs:

Old (deprecated) syntax:

tags = merge(local.tags, map("Name", "my-resource", "Environment", "prod"))

New (correct) syntax:

tags = merge(local.tags, {
  "Name"        = "my-resource"
  "Environment" = "prod"
})

For empty maps, use {} instead of map():

Old:

my_map = map()

New:

my_map = {}

If the error is in an imported module (from Terraform Registry or GitHub), update the module version to one that supports your Terraform version:

module "example" {
  source  = "terraform-aws-modules/vpc/aws"
  version = "~> 5.0"  # Update to a recent version
  # ... rest of configuration
}

Then reinitialize:

terraform init -upgrade

Check the module's documentation or terraform.tf for required_version constraints. Ensure your Terraform version meets the minimum requirement:

terraform version

If needed, upgrade Terraform to a compatible version that supports the modules you're using.

After updating all map() calls, run a fresh plan to confirm the error is resolved:

rm -rf .terraform
terraform init
terraform plan

The plan should now proceed without the 'Call to function map failed' error.

While fixing map(), check for other deprecated functions that may also fail in modern Terraform versions:

- lookup() with 2 arguments: Update to use 3-argument form with default value
- matchkeys(): Use setproduct() and contains() instead
- transpose(): Manually restructure data if needed

See the Terraform language functions documentation to verify your code uses only supported functions.